Sunday9 May 20043:24pm MDT2004-05-09 UTC 2124 back top next  

The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors


Today's issue status: done
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Cover: Last week's most observed small object was 2004 HX53, picked up optically on multiple days, and also reported by radar from the previous week. At left, it is seen as caught by Great Shefford Observatory in England on the 6th. It moved 13'36" while 96 eight-second exposures were made during 2111-2144 UT, so the star trails are longer than can fit in the cropped frame seen here twice-size.

Details: 2004 HX53. 2004 05 06 2111-2144 UT. Mag +19.7. 96x8 second exposures (total exposure 12m 48s). Binned 2x2 and enlarged x2. Motion 25"/min in p.a. 288° object moved 13'36" during exposures. Field 11.25'x12', North up, 0.30m f/6.3 Schmidt-Cassegrain + CCD. J95

Small objects – panel 1/2 Major News for 9 May 2004 back top next  

Small objects
Discovery & follow-up 3-9 May

There are currently 554 near-Earth asteroids listed by the Minor Planet Center and/or JPL with absolute magnitude (brightness) calculated at H greater than 22.0, which roughly converts to a diameter of 135 meters/yards or less. And, despite the full Moon at mid-week, eight of these dim objects were reported as followed by ten observing facilities since last Sunday, as publicly reported through this morning, led by Siding Spring in Australia and Tenagra II Observatory in Arizona. Also reported this week were observations from April for four others. Only one asteroid discovery was announced all week, and it was a small one, 2004 JB, found with the Spacewatch 1.8m telescope in Arizona on May 1st.

The most watched small object was 2004 HX53, and this week it was also reported that Arecibo in Puerto Rico had caught it with radar last week (Friday and Saturday). It made the closest known small object flyby last week, at 12.4 lunar distances Friday.

One of the week's most interesting small object catches was of 2004 HG12. Erich Meyer took advantage of the lunar eclipse to nail 7.604 days onto what had been a 6.049-day observing arc. See the May 5th "cover" for more about that.

No small object close flybys are predicted for next week or, for that matter, for the next month and a half.

<< previous report | skip table | Small objects table >>

If an asteroid's orbit brings it to within 0.05 AU of Earth's orbit, it is categorized as "potentially hazardous" unless it has an absolute magnitude H greater than 22.0, which corresponds to a diameter on the order of 135 meters/yards. Larger H is dimmer, thus smaller. And 0.05 astronomical units (AU) is about 19.5 times the distance between Earth and Moon (0.00256 AU).

Notes: Diameters in the following observation summary table are rough best estimates from a standard but very inexact H-to-size formula using H (absolute magnitude) from the JPL NEO Orbital Elements page, source also for Earth MOID (minimum orbital intersection). Other planetary MOIDs are from Lowell Observatory (last updated May 7th). Current Minor Planet Center H is also given, along with the original H from each object's discovery MPEC. Priorities and visibilities are from the European Spaceguard Central Node (SCN), from which the last data was available May 7th.

Small objects – panel 2/2 (table) Major News for 9 May 2004 back top next  

Small object observation summary for 3-9 May

H = absolute magnitude (brightness), from which size is roughly estimated   —   m/yd = meters/yards   —   [cross index]
All objects had observations reported last week. Those on a light-blue background had observations from only before the week.


Object
Estimated
diameter
JPL
H
MPC
H
Discovery
H in MPEC
Earth
MOID
European Spaceguard Central Node
priority/visibility/campaign
2004 HH20
Amor
34 m/yd24.9825.124.7 2004-H510.03015 AUNecessary, visibility ends 17 May
2004 HH20 was observed on 30 April with the Australian Natl. Univ. (ANU) Obs. 1.0m telescope.
2004 HD
Amor
40 m/yd24.6524.824.5 2004-H190.03049 AUUseful, visibility ends 6 Jun.
2004 HD was observed on 2 May by Tenagra II Obs.
2004 GD2
Apollo
52 m/yd24.0824.324.2 2004-G280.02000 AUUseful, visibility ends 7 Jun.
2004 GD2 was observed on 2 May by Tenagra II Obs. It has an MOID of 0.001 AU with Mars.
2004 GZ14
Apollo
53 m/yd24.0123.924.0 2004-G440.02769 AU
2004 GZ14 was reported this last week as observed on 21 April by KLENOT.
2004 GD
Apollo
62 m/yd23.6823.723.8 2004-G170.00600 AU
2004 GD was observed on 18 April by KLENOT. It has an MOID of 0.033 AU with Venus.
2004 HT38
Amor
70 m/yd23.4223.623.6 2004-H710.09868 AUNecessary, visibility ends 31 May
2004 HT38 was reported this last week as observed on 30 April with the ANU 1.0m telescope.
2004 HX53
Apollo
75 m/yd23.2723.623.8 2004-H800.02065 AUNecessary, visibility ends 10 May
2004 HX53 was observed on 30 April and 1 May by radar from Arecibo (see "images"). And it was observed optically on 2, 4, and 6-7 May by Tenagra II Obs., on 5 and 7 May by Powell Obs., and on 6 May by Great Shefford Obs. (see cover image above). It flew past Earth at 12.4 lunar distances on May 7th.
2004 HQ1
Apollo
has VIs
77 m/yd23.2123.023.0 2004-H380.00229 AUNecessary, visibility ends 3 Jun.
2004 HQ1 was observed on 2 May with the ANU 1.0m telescope and on 7 May by Tenagra II Obs.
2004 JB
Amor
98 m/yd22.7022.722.7 2004-J300.18684 AUNecessary, visibility ends 11 Jun.
NEW: 2004 JB was discovered on 1 May with the Spacewatch 1.8m telescope, was confirmed on 2 May with the Spacewatch 0.9m telescope and on 4 May with the ANU 1.0m telescope. It was announced in MPEC 2004-J30 of 7 May and hasn't been reported since.
2004 HB39
Amor
99 m/yd22.6722.722.5 2004-H740.09312 AUUseful, visibility ends 17 Aug.
2004 HB39 was observed on 30 April with the ANU 1.0m telescope, on 2 May by Desert Moon Obs., and on 2 and 4 May by Tenagra II Obs.
2004 HS56
Amor
130 m/yd22.0822.322.0 2004-H830.03048 AUNecessary, visibility ends 26 May
2004 HS56 was observed on 2 May by Reedy Creek Obs.
2004 HG12
Apollo
137 m/yd21.9622.422.9 2004-H470.02635 AU
2004 HG12 was observed on 4 May by Erich Meyer at Linz Obs. during the lunar eclipse. See the image.

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2004 GD246
2004 GD2926
2004 GZ14246
2004 HB39413, 448 & 926
2004 HD926
2004 HG12540
2004 HH20413
2004 HQ1413 & 926
2004 HS56428
2004 HT38413
2004 HX53251, 649, 926 & J95
2004 JB291, 413 & 691
CodeObservatoryObjects observed (days)
246KLENOT2004 GD & 2004 GZ14
251Arecibo2004 HX53(2)
291Spacewatch 1.8m telescope2004 JB
413Australian National University Observatory 1.0m telescope2004 HB39, 2004 HH20, 2004 HQ1, 2004 HT38 & 2004 JB
428Reedy Creek Obs.2004 HS56
448Desert Moon Obs.2004 HB39
540Linz Obs.2004 HG12
649Powell Obs.2004 HX53(2)
691Spacewatch 0.9m telescope2004 JB
926Tenagra II Obs.2004 GD2, 2004 HB39(2), 2004 HD, 2004 HQ1 & 2004 HX53(4)
J95Great Shefford Obs.2004 HX53
Risk monitoring - panel 1/1 Major News for 9 May 2004 back top next  
Risk monitoring 9 May

No objects with impact solutions are reported in the Sunday Daily Orbit Update MPEC, but the Minor Planet Center Last Observation page is showing that 2004 HM was caught with the Spacewatch 1.8m telescope in Arizona this morning.

Summary Risk Table - sources checked at 2118 UTC, 9 May

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 HZ NEODyS 5/22023-20454-2.39-2.39011.973
JPL 5/22023-20333-2.44-2.44011.973
 2004 HQ1 NEODyS 5/82079-20791-6.74-6.74018.050
JPL 5/3R E M O V E D
 2004 HMJPL 4/292101-21042-5.05-5.05010.990
 2004 GE2JPL 4/242100-21001-6.02-6.02011.811
VI = count of "virtual impactors" (impact solutions)
See A/CC's Consolidated Risk Tables for more and maybe
  newer details, and check the monitors' links for latest info.
Note that only objects recently in view are shown here.
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